1. Field of the Invention
The present invention relates to a method for replacing components of an epicyclic gear mechanism that is used particularly in a wind energy system. The epicyclic gear mechanism has a main axis; a housing that is divided by two parting planes into a drive side section, a center section, and a power take-off side section, whereby the three sections of the housing are lined up along the main axis, and whereby the housing can be separated in the parting planes; a pinion cage, which is mounted to rotate about the main axis in the drive side section of the housing and which has at least one planet bolt that extends along a planet axis that is fixed relative to the pinion cage and runs parallel to the main axis; an internal geared wheel that is disposed in the center section of the housing coaxially to the main axis, fixed on the housing; a sun wheel that is mounted to rotate about the main axis on the power take-off side section of the housing; and at least one planet wheel mounted to rotate on the planet bolt of the pinion cage and meshes both with the internal geared wheel in a first gear tooth engagement and with the sun wheel in a second gear tooth engagement; wherein the drive side section of the housing is mounted in a machine frame. Furthermore, the invention relates to an installation bolt that is particularly suitable for carrying out the method.
2. The Prior Art
Epicyclic gear mechanisms—also called planetary gear mechanisms—having these characteristics have been the state of the art for decades. They have also been used in wind energy systems for quite some time, in order to translate the comparatively low speed of rotation of the rotor into a higher speed of rotation suitable for the generator.
A gear mechanism for a wind energy system, of the type stated initially, is known from DE 101 59 973 A1. The planetary stage of this previously known gear mechanism is followed by an additional spur wheel stage having standing wheels. This arrangement is a common gear mechanism concept in the wind energy sector, because wind energy gear mechanisms must perform translations of up to 90, and this performance is sometimes difficult to implement with a single planetary stage, given the limited construction space in the gondola. A particular feature of the gear mechanism known from DE 101 59 973 A1 is the mounting of the sun shaft. The sun shaft is implemented as a toothed pinion shaft, which means that the sun wheel and the sun shaft form a common element of the gear mechanism. The sun shaft is provided with an axial bore, through which a shaft connected with the pinion cage is inserted along the main axis. In this manner, the sun wheel of the previously known gear mechanism is mounted to rotate in the housing.
In the region of the planetary stage, the housing of the previously known gear mechanism has two parting planes passing through it, which extend normal to the main axis, and divide the gear mechanism housing into three sections. These sections are a drive-like section in the direction of the rotor, a center section that is formed by the internal geared wheel fixed in the housing, and a power take-off section in the direction of the generator. By loosening the bolts that connect the internal geared wheel with the two adjacent sections of the housing, the previously known gear mechanism can be divided in both parting planes. The parting planes therefore run through the axial side surfaces of the internal geared wheel that is fixed in the housing.
In recent times, damage to wind energy systems has become known with remarkable frequency, which is possibly attributable to uncertainties in the dimensions and/or method of operation. The damage relates to the gear mechanisms, among other things, which are fixed in place between rotor and generator, as the core piece of the drive train. Therefore, the gear mechanisms are exposed to negative influences on all sides. The consequences are premature fatigue or even total failure of individual components of the gear mechanism such as wheels and bearings.
These cases of damage can be countered by replacement of components of the gear mechanism that are particularly at risk of failure. Instead of the components originally used, modified replacement components are used, in the dimensioning of which experience from the past is taken into consideration. Furthermore, it is possible to perform preventive maintenance measures in order to retain the system value and fulfill requirements resulting from insurance contracts. All of these measures are supposed to take place inexpensively.
However, the replacement of individual components of a wind energy gear mechanism because of its exposed position involves difficulties that increase costs. Thus, replacement of a planet wheel has required bringing the gear mechanism to the workshop, which in turn requires the gear mechanism to be disassembled and subsequently re-assembled. For this purpose, the system has to be shut down for weeks, in some cases, and an external mobile crane has to be procured, with which the gear mechanism removed from the drive train must be lifted from the tower. In some systems, the rotor also has to be taken off, since it is partially mounted in the gear mechanism. The resulting repair costs reach dimensions that make the replacement of components that are at risk of damage or have already been damaged appear uneconomical, in light of the low earnings of a wind energy system.
DE 199 55 516 C1 proposes a wind energy system that has a particularly strong on-board crane for lifting, for one thing, and has a large-area opening in the floor of the gondola, for another. Both these features make it possible to lower heavy and bulky units of the drive train, such as the gear mechanism, from the tower without using an external mobile crane, and subsequently pull them up again. Such wind energy systems have not become widespread to any noteworthy extent up to now. Instead, in most cases, older systems have to be repaired, which do not have a sufficiently powerful on-board crane and whose opening in the gondola floor measures at most a square meter, which is by far not enough to pass the gear mechanism through.